Endometrial Receptivity Analysis (ERA)

The ERA test analyzes the gene expression pattern of a small endometrial biopsy taken during a mock cycle to determine when the endometrium is most receptive ("the window of implantation"). Some women have a shifted window and may benefit from a personalized embryo transfer (pET) with adjusted progesterone timing.

ERA is typically offered after one or more failed transfers with good-quality embryos and a normal uterine cavity. Evidence on routine use is mixed — a large randomized trial did not show benefit in unselected patients — but it may help a subset with repeated implantation failure. The biopsy is collected on the day that would normally be transfer day in a mock protocol.